Quote:
Originally Posted by hinged_bap
I've had ( intermittent ) low speed brake pedal crunch for some time now, the rear hubs have been renewed - amongst other things ( and the rusty backplates cleaned up to preclude rust flakes attaching to the reluctor rings ) but still no joy. After an inconclusive ABS pulse test session yesterday afternoon. Last night, the ABS fault light came on and I now have a solid ABS fault at static and out driving. This morning, I disconnected the rear o/s sensor ( at the connector at the rear of the back seat ) and connected a new one ( so obviously the new one isn't in contact with the reluctor ring ). My question is, if the rear o/s sensor was faulty, should the ABS pass static test with my fitting a new sensor in this fashion.
TIA
Bap
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Hi Bap, some interesting info here:
http://http://www.macfadyen998.plus.com/
I had problems with my ABS not so long back. In answer to your question; ABS does a 4 sec test - ECU sends signal to each ABS sensor. If all ok, ABS light goes out, however if after driving a short distance, a fault occurs then ECU registers fault & illuminates ABS light.
If an ABS sensor goes faulty, then the ECU cuts power to the affected unit.
The test is in 3 parts.
1) strip back part of the cables into the ABS plug (see website link for colours)
solid colour is 12v constant, striped is pulse (could be other way round lol)
Using a volt meter, connect + to 12v constant - to good earth, this should give you a 12v reading.
2) raise relevant wheel off the ground. Connect voltmeter + to pulse cable - to ground. Spin the wheel and check readings - 0.67 rested & I think 1.74 with wheel turning. This determines sensor is reading the ring.
3) You'll need a donor set of ABS plug/socket. The idea is to 'bridge' the affected ABS to a known good cable i.e NSF ABS plugged into OSF socket. Its a way of kidding the ECU & usually works & can be good at determining faulty cabling.
My problem was a break somewhere in the loom. In the end I took new cable from the ECU to the affected ABS - hey presto, working ABS again.
Check under the battery compartment tray as this is where the ABS ECU lives & can get water damaged from plenum drain issues.
Another idea would be to disconnect the battery for 30 mins - as this can sometimes reset the ECU.
Hope this helps,
Phil.